This invention relates to a method of storing energy in a two-vessel system in which one vessel contains a first substance comprising two components, one of which is driven off and later becomes absorbed, respectively, by the other component upon the supply of energy to and withdrawal of energy from the system. The invention also includes a system adapted to carry out this method.
Such two-vessel systems comprise two chambers or vessels which are interconnected by at least one or sometimes two conduits, so that an at least substantially closed circulation system is formed.
In a known two-vessel system, which is disclosed in the U.S. Pat. No. 4,186,794 and is primarily designed for heating purposes, one chamber of the system contains a hydrate, particularly Na.sub.2 S.nH.sub.2 O, and the other chamber of the system contains water. When energy is stored (charging) water is distilled away from the hydrate, and the water vapor formed is conducted to the other chamber of the system, where it condenses. When energy is withdrawn, the substance in said one chamber of the system absorbs water vapor from the other vessel or chamber.
In a paper "The Sun energy-no parenthesis" by Gunnar Wettermark and Hans Stymne in the journal VVS 5/1977 a system is described whose one vessel contains a first ammoniate and whose second vessel contains a second ammoniate. The vessels are interconnected by means of a first conduit and a second conduit. At storing ammonium, distills from said one chamber, which has then a high temperature, through said first conduit over to the second vessel which has a low temperature. The first conduit suitably passes through a heat exchanger in which the ammonium is caused to give off heat to air for the heating of rooms or the like. For the extraction of energy a valve is opened in the second conduit in which a turbine is interconnected, ammonium being conducted from the second vessel through the turbine into said one vessel which is now being maintained at the same temperature as the second chamber by a heat exchange means. In this known system the energy stored in a first ammoniate is taken out in the form of mechanical energy. During the charging operation supplied heat energy is stored partly in a second ammoniate as chemical energy, and partly in a store magazine as sensible heat energy.
In the two systems described above the stored energy is taken from the sun by means of solar collectors and heat exchanger windings coupled to the solar collectors and located in the contents of said one chamber.